Geological drilling constitutes an important component in the exploration of minerals such as iron ore. This drilling provides information on lithologies that compose the geological model used in the estimation of resources and reserves. Geological drilling further allows for the analysis of boreholes, in order to determine percentages of ore in later stages of exploration and exploitation.
However, drilling holes are subject to operational factors that can lead to inaccurate conclusions. Such factors include blistering, recovering and contamination of samples, which interfere with the analysis of in situ densities.
Further, various techniques for borehole analysis may be inaccurate. Such techniques for density measurement and lithological contact determination may lead to inaccurate information due to the impossibility of preserving the core interstitial spaces in the drilling holes or the displacement of material during rods withdrawal. In order to minimize possibility of mistakes regarding drilling holes, additional techniques may be used to provide information on the rocks and their natural state, before removal by core drilling.
One way to provide information on lithological contacts or in situ density utilizes gamma-gamma well logging. Gamma-gamma well logging includes the exposure of a borehole wall to the influence of a radioactive source and then counting gamma radiation that is received by a receiver placed a known distance from the source. However, such tools are typically used for oil exploration and not mineral exploration. Due to the different lithologies involved between the two applications, use of the tool needs to be adapted for mineral exploration.